Fix clippy lint `cast_slice_from_raw_parts` #530

Job	Run time
Pass MSRV values to other jobs	2s
nostd/thumbv6m-none-eabi/stable	19s
format/nightly	13s
clippy/stable	27s
cross_test/i686-unknown-linux-gnu/stable	2m 44s
cross_test/s390x-unknown-linux-gnu/stable	9m 38s
miri	11m 5s
cargo-careful	2m 25s
docs/nightly	22s
blas-msrv	43s
tests/1.64.0	3m 36s
tests/stable	2m 52s
tests/beta	2m 48s
tests/nightly	3m 18s
conclusion	3s
	40m 35s

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